TWI879225B - Polyimide film, flexible metal foil clad laminate and electronic component comprising the same - Google Patents

Abstract

The present invention provides a polyimide film having a moisture absorption rate of 0.9% or less and an elongation of 20% or more and 50% or less, and a method for producing the same.

Description

Polyimide film, flexible metal-clad foil laminate and electronic component thereof

The present invention relates to a polyimide film having high dimensional stability to humidity and heat and well-balanced appropriate elongation and a method for producing the same.

Polyimide (PI) is based on a rigid aromatic main chain and an imide ring with excellent chemical stability. It is a polymer material that has the highest level of heat resistance, chemical resistance, electrical insulation, chemical resistance, and weather resistance among organic materials.

Polyimide films have attracted much attention as materials for various electronic devices requiring the above-mentioned properties.

Microelectronic components using polyimide films can be, for example, flexible ultra-thin circuit substrates with high circuit integration, so as to cope with the lightweight and miniaturization of electronic products. Polyimide films are particularly widely used as insulating films for ultra-thin circuit substrates.

The structure of the aforementioned ultra-thin circuit substrate is generally to form a circuit including a metal foil on an insulating film. In a broad sense, such an ultra-thin circuit substrate is called a flexible metal foil clad laminate (Flexible Metal Foil Clad Laminate). When a thin copper plate is used as the metal foil, in a narrow sense, it is also called a flexible copper clad laminate (Flexible Copper Clad Laminate: FCCL).

As a method for manufacturing a flexible metal-clad laminate, for example: (i) a casting method in which polyamide, which is a precursor of polyimide, is cast or coated on a metal foil and then imidized; (ii) a metallization method in which a metal layer is directly provided on a polyimide film by sputtering; and (iii) a lamination method in which a polyimide film and a metal foil are bonded by using heat and pressure using thermoplastic polyimide.

In particular, the metallization method, for example, sputtering a metal such as copper on a polyimide film with a thickness of 20 μm to 38 μm and depositing a tie layer and a seed layer in sequence to produce a flexible metal-clad laminate, has advantages in forming ultra-fine circuits with a pitch of less than 35 μm in the circuit pattern, and is widely used to manufacture flexible metal-clad laminates for COF (chip on film).

The polyimide film actually used in the manufacture of flexible metal-clad laminates is in an environment with varying humidity, temperature, etc.

In particular, polyimide films with high moisture absorption and large moisture expansion coefficient may undergo ion migration due to the high moisture absorption, and absorb moisture during the manufacturing process of the flexible metal-clad laminate. Due to the high moisture expansion coefficient, large dimensional changes may occur, and thus polyimide films with low moisture absorption and moisture expansion coefficient are required.

The matters described in the prior art above are used to help understanding the background of the invention and may include matters that are not known to ordinary technicians in the technical field.

[Prior art document] [Patent document] Patent document 1: Korean patent No. 10-1258432.

[Technical topics]

Therefore, an object of the present invention is to provide a polyimide film having low moisture absorption rate and low moisture absorption expansion coefficient and excellent dimensional stability.

In addition, the present invention aims to provide a polyimide film having excellent thermal dimensional stability (low thermal expansion coefficient and thermal shrinkage rate) and chemical resistance.

On the other hand, the present invention aims to provide a polyimide film having high dimensional stability and well-balanced appropriate elongation.

However, the issues to be solved by the present invention are not limited to the issues mentioned above, and other issues not mentioned can be clearly understood by those skilled in the art from the following description. [Technical Solution]

One aspect of the present invention, which is intended to achieve the above-mentioned purpose, provides a polyimide film, wherein the moisture absorption rate is less than 0.9%, and the elongation is greater than 20% and less than 50%.

Another aspect of the present invention provides a flexible metal-clad laminate comprising the aforementioned polyimide film and a conductive metal foil.

Another aspect of the present invention provides an electronic component including the aforementioned flexible metal-clad foil laminate. [Effect of the invention]

The present invention provides a polyimide film having excellent dimensional stability against humidity and heat, thereby providing a polyimide film which also maintains excellent dimensional stability during a metal foil pressing process.

In addition, the present invention provides a polyimide film having high dimensional stability, well-balanced appropriate elongation, and excellent chemical resistance.

This polyimide film can be applied to various fields of polyimide films requiring excellent dimensional stability, for example, it can be applied to a flexible metal-clad laminated plate manufactured according to a metallization method or an electronic component including such a flexible metal-clad laminated plate.

The terms or words used in this specification and the scope of the patent application shall not be interpreted in a limited manner according to the usual meaning or dictionary meaning, but shall be interpreted only as the meaning and concept that conforms to the technical idea of the invention based on the principle that "the inventor can appropriately define the concept of the term in order to explain his own invention in the best way".

Therefore, the configuration of the embodiment described in this specification is only one of the best embodiments of the present invention, and does not all represent the technical ideas of the present invention. Therefore, it should be understood that there will be various equivalents and modifications that can be substituted at the time of this application.

In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as "including", "having" or "having" are intended to specify the existence of features, numbers, steps, constituent elements or combinations thereof of implementations, and should be understood as not excluding the existence or additional possibility of one or more other features or numbers, steps, constituent elements or combinations thereof in advance.

In this specification, "dianhydride" is meant to include precursors or derivatives thereof, which may not technically be dianhydrides but nevertheless will react with diamines to form polyamides which can in turn be converted into polyimines.

In this specification, "diamine" is meant to include its precursors or derivatives, which may not technically be diamines but will nevertheless react with dianhydrides to form polyamides which can in turn be converted into polyimines.

In this specification, when an amount, concentration or other value or parameter is given by listing a range, a preferred range or a preferred upper limit and a preferred lower limit, regardless of whether the range is disclosed separately, it should be understood that all ranges formed by any pair of any upper range limit value or preferred value and the upper range limit value or preferred value are specifically disclosed.

When a range of numerical values is mentioned in this specification, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within the range. The scope of the present invention is not intended to be limited to the specific values mentioned when defining the range.

In this specification, in "a to b" and "a~b" indicating a numerical range, "to" and "~" are defined as ≥a and ≤b.

The moisture absorption rate of the polyimide film of an embodiment of the present invention can be 0.9% or less, and the elongation can be 20% or more and 50% or less.

For example, the moisture absorption rate may be 0.5% or more.

In one implementation example, the hygroscopic expansion coefficient of the polyimide film in the machine direction (MD) may be 5.0 ppm/%RH or less, and the polyimide film may have a balanced and appropriate elongation while having a low moisture absorption rate and hygroscopic expansion coefficient.

For example, the hygroscopic expansion coefficient in the longitudinal direction (machine direction; MD) may be 1.0 ppm/%RH or more, 2.0 ppm/%RH or 3.0 ppm/%RH or more.

In one implementation example, the thermal expansion coefficient of the polyimide film may be less than 4 ppm/°C, and the thermal shrinkage rate may be less than 0.05%, so that the polyimide film may have high thermal dimensional stability.

For example, the thermal expansion coefficient may be greater than -1.0 ppm/°C, and the thermal shrinkage rate may be greater than 0.001%.

In one embodiment, the polyimide film can be obtained by subjecting a polyimide solution containing a dianhydride component and a diamine component to an imidization reaction at a temperature of 350° C. to 500° C.

On the other hand, if the imidization reaction temperature exceeds the range of the present invention, the moisture absorption rate and the moisture absorption expansion coefficient of the polyimide film will increase, and the dimensional stability of the polyimide film to humidity will decrease.

In addition, if the imidization reaction temperature is lower than the range of the present invention, the elongation of the polyimide film will be greatly reduced.

In one implementation example, the polyimide film of the present case can be obtained by subjecting a polyimide solution containing a dianhydride component and a diamine component to an imidization reaction, wherein the dianhydride component comprises 3,3',4,4'-biphenyltetracarboxylic dianhydride and isomellitic dianhydride, and the diamine component comprises p-phenylenediamine and 2,2'-dimethylbenzidine.

That is, the polyimide membrane of the present invention can be obtained by copolymerizing 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA), p-phenylenediamine (PPD) and 2,2'-dimethylbezidine (m-tolidine), MTD.

The polyimide chain derived from biphenyltetracarboxylic dianhydride has a structure named charge transfer complex (CTC), that is, a regular linear structure in which electron donors and electron acceptors are arranged close to each other, which strengthens the intermolecular interaction.

In addition, pyromellitic dianhydride is a dianhydride component with a relatively rigid structure and can impart appropriate elasticity to the polyimide film, so it is preferred.

On the other hand, biphenyltetracarboxylic dianhydride contains two benzene rings corresponding to the aromatic moiety, whereas pyromellitic dianhydride contains one benzene ring corresponding to the aromatic moiety.

In the dianhydride component, the increase in the content of pyromellitic dianhydride can be understood as an increase in the imide groups in the molecule when the molecular weight is the same. This can be understood as the ratio of the imide groups derived from the aforementioned pyromellitic dianhydride to the imide groups derived from biphenyltetracarboxylic dianhydride in the polyimide polymer chain is relatively increased.

In addition, 2,2'-dimethylbenzidine containing a methyl group as a terminal group can improve the hydrophobicity of the polyimide film and reduce the moisture absorption rate of the polyimide film, and p-phenylenediamine can improve the thermal dimensional stability (low thermal expansion coefficient and low thermal shrinkage rate) of the polyimide film.

In one implementation example, based on the total content of the aforementioned dianhydride components being 100 mol%, the content of the aforementioned 3,3',4,4'-biphenyltetracarboxylic dianhydride can be greater than 45 mol% and less than 55 mol%, the content of the aforementioned pyromellitic dianhydride can be greater than 45 mol% and less than 55 mol%, based on the total content of the aforementioned diamine components being 100 mol%, the content of the aforementioned p-phenylenediamine can be greater than 40 mol% and less than 60 mol%, and the content of the aforementioned 2,2'-dimethylbenzidine can be greater than 40 mol% and less than 60 mol%.

If the content of the dianhydride component and the diamine component exceeds or is lower than the range of the present invention, the thermal expansion coefficient will exceed the range of the present invention.

In one embodiment, based on 100 wt % of the solid content of the polyamide solution, 1.5 wt % or more of triphenyl phosphate, polyethylene glycol or a combination thereof may be included.

The aforementioned triphenyl phosphate, polyethylene glycol or a combination thereof can play a role in pre-blocking the space in the polyimide membrane through which water can pass.

For example, based on 100 wt % solid content of the polyamide solution, the triphenyl phosphate, polyethylene glycol or a combination thereof may contain 1.5 wt % or more, 3 wt % or more, 5 wt % or more, 10 wt % or more, or 15 wt % or more.

As the content of the aforementioned triphenyl phosphate, polyethylene glycol or a combination thereof increases, the elongation, thermal shrinkage and thermal expansion coefficient of the polyimide film will increase.

In addition, when the content of the triphenyl phosphate, polyethylene glycol or a combination thereof is lower than the range of the present invention, the elongation of the polyimide film is significantly reduced even if the imidization reaction temperature is set to 350° C. or higher and 500° C. or lower.

In one implementation example, the difference between the weight loss rate at 200° C. and the weight loss rate at 400° C. of the polyimide film of the present invention measured by a thermogravimetric analyzer may be greater than 1%.

For example, the difference between the weight loss rate at 200° C. and the weight loss rate at 400° C. of the polyimide film of the present invention measured by a thermogravimetric analyzer may be 5% or less.

On the other hand, the gas emission of the polyimide membrane in this case can be greater than 2% and less than 20%.

For example, the gas emission of the polyimide film may be greater than 2% and less than 10%.

In addition, the color a* of the polyimide film of the present invention can be greater than -7.5 and less than 10, the transmittance can be greater than 30% and less than 70%, and the dielectric loss factor measured at 10 GHz can be greater than 0.004 and less than 0.006.

The color a* was measured at room temperature using a colorimeter (Ultrascan pro, Hunter Lab).

In addition, the transmittance at 400-700 nm was measured using HunterLab equipment according to the ASTM D1003 standard.

On the other hand, the aforementioned dielectric loss rate was determined by drying the manufactured polyimide film at 130°C for 30 minutes, aging it in a constant temperature and humidity chamber maintained at 23°C for 24 hours for pretreatment, and then measuring the dielectric properties at a frequency of 10 GHz using the split-pillar dielectric resonator (SPDR) measurement method using Keysight Technologies' ENA.

In the present invention, the production of polyamine acid can be carried out by the following methods, for example: (1) A method in which the entire amount of the diamine component is added to a solvent, and then the dianhydride component is added so that the diamine component and the dianhydride component are substantially equimolar and polymerized; (2) A method in which the entire amount of the dianhydride component is added to a solvent, and then the diamine component is added so that the diamine component and the dianhydride component are substantially equimolar and polymerized; (3) A method in which a portion of the diamine component is added to a solvent, and then a portion of the dianhydride component is mixed at a ratio of about 95 to 105 mol% relative to the reaction component, and then the remaining diamine component is added, and then the remaining dianhydride component is added so that the diamine component and the dianhydride component are substantially equimolar and polymerized; (4) The method comprises adding a dianhydride component to a solvent, mixing a portion of the diamine compound at a ratio of 95 to 105 mole percent relative to the reaction component, adding other dianhydride components, and then adding the remaining diamine components, so that the diamine component and the dianhydride component are substantially equal in mole and polymerizing; (5) The method comprises reacting a part of the diamine component with a part of the dianhydride component in a solvent so that one of them is excessive to form a first composition, reacting a part of the diamine component with a part of the dianhydride component in another solvent so that one of them is excessive to form a second composition, and then mixing the first composition and the second composition to complete polymerization. At this time, when the diamine component is excessive when forming the first composition, the dianhydride component is excessive in the second composition, and when the dianhydride component is excessive in the first composition, the diamine component is excessive in the second composition, and the first composition and the second composition are mixed so that the total diamine component and the dianhydride component used in the reaction are substantially equimolar and then polymerized.

In a specific example, the method for manufacturing a polyimide film of the present invention may include: providing a polyimide solution obtained from a dianhydride component and a diamine component; mixing triphenyl phosphate, polyethylene glycol or a combination thereof in the polyimide solution; casting the polyimide solution mixed with triphenyl phosphate, polyethylene glycol or a combination thereof on a support and then heating to manufacture a self-supporting film of the polyimide solution; and imidizing and stretching the self-supporting film at a temperature above 350°C and below 500°C to manufacture a polyimide film.

In the present invention, the polymerization method of the polyamic acid as described above can be defined as a random polymerization method, and the polyimide film made from the polyamic acid of the present invention manufactured by the above process can be preferably applied in maximizing the effect of improving the flatness of the present invention.

However, the aforementioned polymerization method has limitations in terms of exerting the various excellent properties of the polyimide chain derived from the dianhydride component because the length of the repeating unit in the polymer chain described above is relatively short. Therefore, the polymerization method of polyamide that can be preferably utilized in the present invention can be block polymerization.

On the other hand, the solvent used for synthesizing polyamine is not particularly limited, and any solvent can be used as long as it can dissolve polyamine, but an amide solvent is preferred.

Specifically, the aforementioned solvent can be an organic polar solvent, and more specifically, can be an aprotic polar solvent, for example, can be one or more selected from the group consisting of N,N-dimethylformamide (DMF), N,N-dimethylacetamide, N-methylpyrrolidone (NMP), γ-butyrolactone (GBL), and diglyme (Diglyme), but is not limited thereto and can be used alone or in combination of two or more as needed.

In one example, the aforementioned solvent may preferably be N,N-dimethylformamide and N,N-dimethylacetamide.

In addition, in the polyamide manufacturing process, fillers may be added for the purpose of improving various film properties such as slip, thermal conductivity, corona resistance, and ring hardness. The added fillers are not particularly limited, and preferred examples include silicon dioxide, titanium oxide, aluminum oxide, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, and mica.

The particle size of the filler is not particularly limited and can be determined according to the film properties to be modified and the type of filler added. Generally speaking, the average particle size is 0.05 μm to 100 μm, preferably 0.1 μm to 75 μm, more preferably 0.1 μm to 50 μm, and particularly preferably 0.1 μm to 25 μm.

If the particle size is below this range, the modification effect is difficult to show, and if it exceeds this range, the surface properties may be greatly damaged or the mechanical properties may be greatly reduced.

In addition, the amount of filler added is not particularly limited and can be determined according to the film properties to be modified or the filler particle size, etc. Generally speaking, the amount of filler added is 0.01 to 100 parts by weight, preferably 0.01 to 90 parts by weight, and more preferably 0.02 to 80 parts by weight, relative to 100 parts by weight of polyimide.

If the amount of filler added is below this range, the modifying effect of the filler is difficult to be exhibited, and if it exceeds this range, there is a possibility that the mechanical properties of the film will be greatly damaged. The method of adding the filler is not particularly limited, and any known method can be used.

The present invention provides a flexible metal-clad laminate comprising the polyimide film and a conductive metal foil.

The metal foil used is not particularly limited, but when the flexible metal foil laminate of the present invention is used for electronic equipment or electrical equipment, it can be, for example, a metal foil including copper or a copper alloy, stainless steel or an alloy thereof, nickel or a nickel alloy (including 42 alloy), aluminum or an aluminum alloy.

Among common flexible metal foil laminated plates, rolled copper foil and electrolytic copper foil are widely used and can be preferably used in the present invention. In addition, a rust-proof layer, a heat-resistant layer or an adhesive layer can also be coated on the surface of these metal foils.

In the present invention, the thickness of the metal foil is not particularly limited as long as it is a thickness that can fully exert its function according to its application.

The flexible metal foil-clad laminate of the present invention can be obtained by laminating, coating, sputtering or vapor-depositing metal foil on at least one side of the aforementioned polyimide film.

In addition, the flexible metal-clad laminate can be used as a two-layer FCCL, and can be used in mobile phones, displays (LCD, PDP, OLED, etc.), and can be used as FPCB and COF.

The electronic component including the aforementioned flexible metal foil laminate may be, for example, a communication circuit for a portable terminal, a communication circuit for a computer, or a communication circuit for aerospace, but is not limited thereto.

The following describes the functions and effects of the invention in more detail by using specific manufacturing examples and embodiments of the invention. However, such manufacturing examples and embodiments are only provided as examples of the invention, and the scope of the invention is not limited thereby.

Production example: Production of polyimide film

The polyimide film of the present invention can be produced by the following common method known in the industry: First, the dianhydride and the diamine component are reacted in an organic solvent to obtain a polyimide solution.

The dianhydride and diamine components can be added in the form of powder, agglomerate or solution. Preferably, they are added in the form of powder at the initial stage of the reaction and in the form of solution after the reaction in order to adjust the polymerization viscosity.

The obtained polyamine solution, after being mixed with triphenyl phosphate, polyethylene glycol or a combination thereof, can be mixed with an imidization catalyst and a dehydrating agent and coated on a support.

Examples of the catalyst used include tertiary amines (e.g., isoquinoline, β-picoline, pyridine, etc.), and examples of the dehydrating agent include acid anhydrides, but are not limited to these. In addition, the support used above may include, for example, a glass plate, an aluminum foil, a circulating stainless steel belt, or a stainless steel drum, but are not limited to these.

The film coated on the aforementioned support is gelled on the support by dry air and heat treatment.

The gelled film is separated from the support and heat treated to complete drying and imidization.

The film that has completed the above heat treatment can be heat treated under a predetermined tension to remove the residual stress inside the film that occurs during the film forming process.

Specifically, 500 ml of DMF was added while nitrogen was injected into a reactor equipped with a stirrer and a nitrogen injection/exhaust pipe, and the reactor temperature was set to 30°C. Then, 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) and 2,2'-dimethylbenzidine (MTD) were added in an adjusted ratio and a predetermined order and completely dissolved. Then, the temperature of the reactor was raised to 40°C in a nitrogen atmosphere and stirring was continued for 120 minutes while heating, thereby producing a polyamide with a primary reaction viscosity of 1500 cP.

Then, the content of triphenyl phosphate (TPP) and/or polyethylene glycol (PEG) is adjusted and added.

The polyamide thus produced is stirred so that the final viscosity reaches 100,000 to 120,000 cP.

After adjusting the content of catalyst and dehydrating agent and adding them to the final polyimide prepared, the imidization process temperature was adjusted and the polyimide film was manufactured using a coater.

The content of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride is 50 mol%, the content of the aforementioned pyromellitic acid dianhydride is 50 mol%, based on the total content of the aforementioned diamine component being 100 mol%, the content of the aforementioned p-phenylenediamine is 50 mol% or more, and the content of the aforementioned 2,2'-dimethylbenzidine is 50 mol%.

Examples and Comparisons example

The manufacturing was carried out according to the above manufacturing example, except that as shown in Table 1 below, the content of triphenyl phosphate (TPP) and/or polyethylene glycol (PEG) and the imidization process temperature of the embodiment and the comparative example were adjusted to manufacture the polyimide membrane.

[Table 1] TPP content (weight % based on polyamide solid content) PEG content (weight % based on polyamide solid content) Imidization process temperature (℃) Embodiment 1 5 0 471 Embodiment 2 5 0 445 Embodiment 3 5 0 440 Embodiment 4 5 5 470 Embodiment 5 5 0 380 Embodiment 6 10 0 380 Embodiment 7 15 0 380 Comparison Example 1 0 0 536 Comparison Example 2 0 0 380 Comparison Example 3 0 0 340 Comparison Example 4 10 0 340 Comparison Example 5 0 0 300 Comparison Example 6 10 0 300

The moisture absorption rate, elongation, moisture absorption expansion coefficient in the machine direction (MD), thermal expansion coefficient, and thermal shrinkage rate of the manufactured polyimide film were measured and are shown in Table 2 below.

(1) Moisture absorption measurement

Moisture absorption rate was measured according to the ASTM D 570 method. The polyimide film was cut into a rectangular piece of 5 cm × 5 cm to produce a test piece. The cut test piece was dried in an oven at 50°C for more than 24 hours and then its weight was measured. The measured test piece was immersed in water at 23°C for 24 hours and then its weight was measured again. The weight difference obtained was expressed as % and measured.

(2) Elongation measurement

The elongation was measured using an Autograph universal testing machine (Shimadzu Corporation, AG-IS) according to the method of ASTM D882.

(3) Hygroscopic expansion coefficient measurement

The coefficient of hygroscopic expansion (CHE) is obtained by applying a minimum weight (about 1 g for a 25 mm × 150 mm sample) so that the multilayer polyimide film does not loosen. In this state, the humidity is adjusted to 3% RH at 25°C, and then the film is allowed to absorb moisture until it is completely saturated and the size is measured. Then, the humidity is adjusted to 90% RH, and the film is saturated and absorbed in the same way, and the size is measured. The dimensional change rate is measured from the results of the two.

(4) Thermal expansion coefficient measurement

The coefficient of thermal expansion (CTE) was measured using a TA company thermomechanical analyzer (Q400 model). The polyimide film was cut into 4mm wide and 20mm long pieces, and the sample measurement length was 16mm. At this time, the sample measurement length direction was the TD direction.

In a nitrogen atmosphere, the temperature was raised from room temperature to 400°C at a rate of 10°C/min while applying a tension of 0.05N, and then the slope in the 200°C range was measured at 50°C while cooling at a rate of 10°C/min. That is, the thermal expansion coefficient is equivalent to the slope measured during the cooling process after the temperature is raised.

(5) Thermal shrinkage measurement

Thermal shrinkage was measured according to IPC_TM_650 2.2.4.

Specifically, polyimide membrane test pieces were prepared by punching holes at intervals of 25 cm and 23 cm using a punching machine, and the dimensions between the holes before processing were measured.

The fabricated samples were stored at 200°C for 2 hours and then placed at 23°C and 50% RH for 24 hours. The post-treatment dimensions between the pores of the samples were then measured.

The dimensional changes of the polyimide film specimens before and after treatment were calculated in percentage.

[Table 2] characteristic Moisture absorption rate (%) Elongation(%) CHE (ppm/%RH) CTE (ppm/℃) Thermal shrinkage rate (%) Embodiment 1 0.70 46 3.9 0.7 0.012 Embodiment 2 0.61 44 3.7 0.1 0.007 Embodiment 3 0.78 42 4.3 1.0 0.002 Embodiment 4 0.63 37 4.5 1.7 0.033 Embodiment 5 0.47 21.0 3.9 -0.6 0.030 Embodiment 6 0.45 28.0 3.7 1.7 0.036 Embodiment 7 0.43 34.0 5.0 3.5 0.048 Comparison Example 1 0.88 45 5.3 1.8 0.040 Comparison Example 2 0.81 7.0 4.1 -2.3 0.019 Comparison Example 3 0.79 5.0 4.6 -1.8 0.022 Comparison Example 4 0.38 19.0 5.2 -0.2 0.023 Comparison Example 5 0.91 5.0 6.0 3.1 0.054 Comparison Example 6 0.58 11.0 4.2 0.1 0.012

As shown in Table 2 above, the moisture absorption rate of the polyimide films of Examples 1 to 7 is less than 0.9%, the elongation is greater than 20% and less than 50%, the moisture absorption expansion coefficient in the MD (Machine direction) direction is less than 5.0 ppm/%RH, the thermal expansion coefficient is less than 4ppm/°C, and the thermal shrinkage rate is less than 0.05%.

It shows that as the imidization process temperature decreases, the elongation and thermal shrinkage of the polyimide film tend to decrease.

In addition, when both TPP and PEG are used, the elongation of the imide film decreases, the CTE increases, and the moisture absorption rate decreases, compared with the case where only TPP is used.

In addition, it is shown that as the TPP content increases, the elongation, CTE and thermal shrinkage of the polyimide film tend to increase.

On the other hand, the imidization process temperature of Comparative Example 1 exceeds 500° C., and TPP and PEG are not included. Compared with the polyimide membrane of the embodiment, the moisture absorption rate and moisture expansion coefficient of the polyimide membrane of Comparative Example 1 are increased.

In addition, the imidization process temperature of Comparative Example 2 is above 350° C. and below 500° C., but does not contain TPP and PEG. Compared with the polyimide film of the embodiment, the elongation of the polyimide film of Comparative Example 2 is very low.

On the other hand, the imidization process temperature of Comparative Examples 3 and 5 is lower than 350° C., and TPP and PEG are not included. Compared with the polyimide film of the embodiment, the elongation of the polyimide film of Comparative Examples 3 and 5 is very low.

In particular, the polyimide film of Comparative Example 5 has higher moisture absorption and thermal shrinkage than the polyimide film of the embodiment.

The polyimide films of Comparative Examples 4 and 6 contain the same amount of TPP as the polyimide film of Example 6, but the process temperature is lower than 350°C. Compared with the polyimide film of Example 6, the elongation of the polyimide films of Comparative Examples 4 and 6 is reduced and the hygroscopic expansion coefficient is increased.

The gas emission of the manufactured polyimide membrane was measured and is shown in Table 3 below.

(6) Gas emission measurement

The weight of the polyimide membrane at 30°C and at 450°C was measured using a thermogravimetric analyzer (TGA). The mass reduction of the polyimide membrane at 450°C compared to the polyimide membrane at 30°C was calculated as a percentage to express the gas emission.

[Table 3] Gas emissions (%) Embodiment 1 2.4 Embodiment 2 3.237 Embodiment 3 3.2 Embodiment 4 3.2 Embodiment 5 4.2 Embodiment 6 7.2 Embodiment 7 9.7

As shown in Table 3 above, the gas emission of the polyimide membranes of Examples 1 to 7 is greater than 2% and less than 20%.

In addition, the difference between the weight loss rate at 200° C. and the weight loss rate at 400° C. of the polyimide films of Examples 1 to 7 measured by a thermogravimetric analyzer is greater than 1%.

As an example, the results of the measurement of the polyimide film of Example 2 using a thermogravimetric analyzer are shown in Table 1.

That is, the polyimide films of Examples 1 to 7 of the present invention have low moisture absorption and low moisture expansion coefficient, excellent dimensional stability, and show balanced elongation characteristics. In addition, they have excellent thermal dimensional stability (low thermal expansion coefficient and thermal shrinkage) and chemical resistance.

The embodiments of the polyimide film and the method for producing the polyimide film of the present invention are only to enable the general skilled person in the technical field to which the present invention belongs to easily implement the preferred embodiments of the present invention, and are not limited to the aforementioned embodiments. Therefore, the scope of the rights of the present invention is not limited thereby. Therefore, the true technical protection scope of the present invention should be determined according to the technical idea of the accompanying patent application scope. In addition, it is self-evident for practitioners that various substitutions, deformations and changes can be realized within the scope of the technical idea of the present invention, and it is self-evident for practitioners that the parts that can be easily changed by practitioners are also included in the scope of the rights of the present invention.

without

FIG. 1 is a result of measuring the polyimide membrane of Example 2 of the present invention using a thermogravimetric analyzer.

Claims (11)

A polyimide film, wherein the moisture absorption rate of the polyimide film is less than 0.9%, and the elongation is greater than 20% and less than 50%, wherein the polyimide film comprises a polyimide containing a dianhydride component and a diamine component as polymerization units, wherein the diamine component comprises p-phenylenediamine and 2,2'-dimethylbenzidine, wherein, based on the total content of the diamine component being 100 mol%, the content of p-phenylenediamine is greater than 40 mol% and less than 60 mol%, and the content of 2,2'-dimethylbenzidine is greater than 40 mol% and less than 60 mol%. The polyimide film as claimed in claim 1, wherein the polyimide film has a hygroscopic expansion coefficient in a machine direction (MD) of 5.0 ppm/%RH or less. The polyimide film as described in claim 1, wherein the thermal expansion coefficient of the polyimide film is less than 4 ppm/°C, and the thermal shrinkage rate is less than 0.05%. The polyimide film as claimed in claim 1, wherein the polyimide film is obtained by subjecting a polyamic acid solution containing the dianhydride component and the diamine component to an imidization reaction at a temperature of 350° C. to 500° C. The polyimide film as recited in claim 1, wherein the polyimide film is obtained by subjecting a polyamide solution containing the dianhydride component and the diamine component to an imidization reaction, wherein the dianhydride component contains 3,3',4,4'-biphenyltetracarboxylic dianhydride and pyromellitic dianhydride. The polyimide film as described in claim 5, wherein, based on the total content of the aforementioned dianhydride component being 100 mol%, the content of the aforementioned 3,3',4,4'-biphenyltetracarboxylic dianhydride is greater than 45 mol% and less than 55 mol%, and the content of the aforementioned pyromellitic dianhydride is greater than 45 mol% and less than 55 mol%. The polyimide membrane as described in claim 4, wherein, based on the solid content of the polyimide solution being 100% by weight, it contains 1.5% by weight or more of triphenyl phosphate, polyethylene glycol or a combination thereof. The polyimide film as claimed in claim 1, wherein the difference between the weight loss rate at 200° C. and the weight loss rate at 400° C. of the polyimide film measured by a thermogravimetric analyzer is 1% or more. A flexible metal-clad laminate comprising a polyimide film as described in any one of claims 1 to 8 and a conductive metal foil. A flexible metal foil-clad laminate as recited in claim 9, wherein the metal foil is formed by coating, sputtering or vapor deposition. An electronic component includes the flexible metal-clad laminate as recited in claim 10.